Summary & Master Memory Capsule

Master Memory Capsule — Alcohols, Phenols & Ethers

A one-glance revision sheet for the morning of your Board, JEE or NEET paper.

Classification & naming: alcohols are mono/di/tri-hydric and 1°/2°/3°; IUPAC = alkanol; ethers = alkoxyalkane (smaller group = alkoxy on the larger parent chain); simple (symmetrical) vs mixed ethers.

Preparation — The Routes to Remember

Alcohols: (1) from alkenes — acid hydration (Markovnikov) and hydroboration-oxidation (anti-Markovnikov, syn); (2) reduction of aldehydes (→1°), ketones (→2°), and acids/esters (LiAlH$_4$ →1°); (3) Grignard — HCHO→1°, other aldehydes→2°, ketones→3°.

Phenol: from haloarene (Dow process), benzenesulphonic acid (NaOH fusion), diazonium salt (warm dilute acid), and the industrial cumene process (cumene → cumene hydroperoxide → phenol + acetone).

Ethers: Williamson synthesis (alkoxide + 1° alkyl halide, SN2 — the route to mixed ethers) and dehydration of 1° alcohols (conc. H$_2$SO$_4$, 413 K → symmetrical ether).

Properties, Acidity & Key Reactions

Physical: hydrogen bonding makes alcohols/phenols boil high and dissolve in water; ethers have no intermolecular H-bonding → low b.p. (but the O atom accepts H-bonds from water, so lower members are still water-soluble).

Acidity ladder: carboxylic acid > phenol > water > alcohol. Phenol's strength comes from resonance stabilisation of the phenoxide ion. EWG (-NO$_2$) at o/p increases acidity; EDG (-CH$_3$, -OCH$_3$) decreases it.

Alcohols: with Na → alkoxide; esterification; with HX/PCl$_3$/PCl$_5$/SOCl$_2$ → R-X; dehydration (3°>2°>1°, Saytzeff); oxidation (1°→aldehyde→acid, 2°→ketone, 3°→resistant).

Phenols: acidity (NaOH); EAS (bromine water → 2,4,6-tribromophenol); nitration; sulphonation; Kolbe → salicylic acid; Reimer-Tiemann → salicylaldehyde; FeCl$_3$ → violet.

Ethers: cleavage by HX (HI > HBr > HCl); anisole → phenol + CH$_3$I; anisole EAS (-OR is activating, o/p-directing).

Named Tests & Last-Minute Triggers

Distinguishing tests: Lucas (conc. HCl + ZnCl$_2$): 3° immediate, 2° ~5 min, 1° no reaction at RT. Victor Meyer: 1° red, 2° blue, 3° colourless. Neutral FeCl$_3$: phenol → violet (alcohol → none). NaHCO$_3$: effervescence only with carboxylic acids (not phenols).

Commercial alcohols: methanol (wood spirit; CO + 2H$_2$ over ZnO-Cr$_2$O$_3$; toxic — blindness); ethanol (fermentation; denatured spirit; power alcohol).

One-line recall: Markovnikov vs anti-Markovnikov; phenoxide resonance → acidity; EWG up / EDG down; dehydration & Lucas follow 3°>2°>1°; Kolbe = salicylic acid, Reimer-Tiemann = salicylaldehyde, Williamson = ether; HX cleaves ethers, anisole → phenol + CH$_3$I.